Metal film and manufacturing method of the metal film, and semiconductor device and method of manufacturing the semiconductor device

ABSTRACT

A metal film, a manufacturing method of the metal film, semiconductor device, and a manufacturing method of semiconductor device are provided with high crack resistance (higher hardness) during wire bonding. The Metal film has first metal crystal grains, and the second metal crystal grains. Each of the first metal crystal grains has dislocations. Each of the second metal crystal grains has no dislocations. The number of the first metal crystal grains having the dislocations is larger than the number of the second metal crystal grains having no dislocations.

CROSS-REFERENCE TO RELATED APPLICATIONS

The disclosure of Japanese Patent Application No. 2022-094618 filed onJun. 10, 2022, including the specification, drawings and abstract isincorporated herein by reference in its entirety.

BACKGROUND

The present invention relates to a metal film, a method formanufacturing the metal film, a semiconductor device, and a method formanufacturing the semiconductor device.

In Japanese Unexamined Patent Application Publication No. 2007-165663(Patent Document 1), a stress relaxing film is formed on a conductivefilm in order to reduce a warpage of a semiconductor wafer. Theconductive film becomes as a gate pad or a source pad, and is made ofaluminum (Al) or the like. The conductive film is formed by sputtering.

SUMMARY

The aluminum pads are required to have high crack resistance (highhardness) during wire bonding.

Other objects and novel features will become apparent from thedescription of this specification and the accompanying drawings.

According to an embodiment of a metal film, a number of first metalgrains having dislocations is larger than a number of second metalgrains having no dislocations.

The semiconductor device according to an embodiment includes the metalfilm as a bonding pad or a wiring.

According to the metal film according to a manufacturing method of theembodiment, the dislocations is formed in the metal film by performingannealing in which metal grains recrystallize after point defects areintroduced into the metal film.

According to manufacturing method of the semiconductor device accordingto an embodiment, the metal film is formed as the bonding pad or thewiring.

According to the above-described embodiment, the metal film having highcrack resistance (high hardness) during wire bonding, a method formanufacturing the metal film, the semiconductor device including themetal film, and a method for manufacturing the semiconductor device arerealized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view showing a configuration of a metal filmaccording to an embodiment.

FIG. 2 is a cross-sectional view showing a configuration of a IGBT(Isolated Gate Bipolar Transistor) having the metal film shown in FIG. 1.

FIG. 3 is a cross-sectional view showing a configuration of asemiconductor package having the IGBT shown in FIG. 2 .

FIG. 4 is a cross-sectional view illustrating a first step of amanufacturing method of the metal film according to the embodiment.

FIG. 5 is a cross-sectional view illustrating a second step of themanufacturing method of the metal film according to the embodiment.

FIG. 6 is a cross-sectional view illustrating a third step of themanufacturing method of the metal film according to the embodiment.

FIG. 7 is a plan view showing a configuration of a photoresist mask fora selectively ion-implantation the region to be wire bonded.

FIG. 8 is a cross-sectional view of the metal film according to acomparative embodiment not performed to the ion-implantation.

FIG. 9 is a cross-sectional view of the metal film performed to theion-implantation with aluminum.

FIG. 10 is a cross-sectional view of a silicon implanted metal film.

FIG. 11 is a cross-sectional view of a metal film according to acomparative embodiment annealed without ion-implantation.

FIG. 12 is a cross-sectional view of the metal film annealed afterion-implantation with aluminum.

FIG. 13 is a cross-sectional view of the metal film annealed afterion-implantation with silicon.

FIG. 14 shows a degree of relaxation of an inner stress of the metalfilm by ion-implantation.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present disclosure will be described indetail with reference to the drawings. In the specification anddrawings, the same or corresponding components are denoted by the samereference numerals, and a repetitive description thereof is notrepeated. In the drawings, for convenience of explanation, theconfiguration or manufacturing method may be omitted or simplified.

Note that a plan view in this specification means a viewpoint viewedfrom a direction perpendicular to a first surface FS of a semiconductorsubstrate. A planar shape also means a shape in plan view. Also, anopening area means an area of the opening in plan view.

(Structure of a Metal Film)

First, a configuration of a metal film according to an embodiment willbe described with reference to FIG. 1 .

As shown in FIG. 1 , the metal film MF is made of a material containingat least one selected from the group consisting of aluminum, tungsten(W), copper (Cu), cobalt (Co), and nickel (Ni). The metal film MF ismade of a material containing, for example, aluminum, pure aluminum, analloy of aluminum and silicon (Si), an alloy of aluminum and copper, oran alloy of aluminum, silicon and copper. The metal film MF has athickness of, for example, 1 micrometer or more and 4 micrometers orless.

The metal film MF has a plurality of metal crystal grains GR. Theplurality of metal crystal grains GR includes first metal crystal grainsGR2, GR3 and GR4 having dislocations DL and second metal crystal grainsGR1 and GR5 having no dislocations DL. The number the first metalcrystal grains GR2, GR3 and GR4 having dislocations DL is greater thanthe number of the second metal crystal grains GR1 and GR5 having nodislocations DL.

The metal film MF has the first surface FS and a second surface SSfacing each other. Each of the plurality of metal crystal grains GRextends from the first surface FS toward the second surface SS andreaches the second surface SS. The density of dislocations DL in each ofthe first metal crystal grains GR2, GR3 and GR4 is 60 particles/squaremicrometer or more. Further, the density of dislocations DL in each ofthe first metal crystal grains GR2, GR3 and GR4 may be 75particles/square micrometer or more.

A mean crystal grain size of the plurality of the metal crystal grainsGR is 1 micrometer or more and 5 micrometers or less. The mean crystalgrain size of the plurality of the metal crystal grains GR may be 1.7micrometers or less. A hardness of the metal film MF is 0.96 GPa ormore. The hardness of the metal film MF may be 1.17 GPa or more.

The metal film MF may have third metal crystal grains GRA. The thirdmetal crystal grains GRA are located on grain boundaries GB of the metalcrystal grains GR. The third metal crystal grain GRA may be arrangedapart from both the first surface FS and the second surface SS of themetal film MF. One third metal crystal grain GRA may be located on onegrain boundary GB, and the plurality of third metal crystal grains GRAmay be located on the one grain boundary GB. In addition, the thirdmetal crystal grain GRA may be located on each of the grain boundariesGB.

The third metal crystal grains GRA are made of a material other than thefirst metal crystal grains GR2, GR3 and GR4, and the second metalcrystal grains GR1 and GR5. When each of the first metal crystal grainsGR2, GR3 and GR4, and the second metal crystal grains GR1 and GR5 aremade of a material containing aluminum, the third metal crystal grainsGRA may be made of, for example, a material containing silicon orcopper. (Configuration of the semiconductor device) Next, thesemiconductor device having the metal film MF of the present embodimentwill be described with reference to FIG. 2 and FIG. 3 by exemplifying aconfiguration of an IGBT.

As shown in FIG. 2 , an electric element formed in the semiconductorsubstrate SB is, for example, the IGBT. The IGBT mainly includes a p+collector region CR, a n+ region HR, a n-drift region DRI, a p-type baseregion BR, a p+ contact region CON, a n+ emitter region ER, and a gateelectrode GE.

The p+ collector region CR is arranged on a first main surface FMS ofthe semiconductor substrate SB. The n+ region HR is arranged on the p+collector region CR (on a second main surface SMS with respect to the p+collector region CR). The n+ region HR configures a pn junction with thep+ collector region CR.

A n− drifting region DRI is arranged on the n+ region HR (on the secondmain surface SMS with respect to the n+ region HR). the n− drift-regionDRI is in contact with the n+ region HR. the n− drift-region DRI has ann-type impurity concentration lower than the n-type impurityconcentration of the n+ region HR.

The p-type base-region BR is arranged on the n− drift-region DRI (thesecond main surface SMS side with respect to n− drift-region DRI). Thep-type base-region BR configures the pn junction with the n−drift-region DRI.

The p+ contact region CON and the n+ emitter region ER are arranged onthe p-type base region BR (on the second main surface SMS side withrespect to the p-type base region BR). Each of the p+ contact region CONand the n+ emitter region ER is arranged on the second main surface SMSof the semiconductor substrate SB.

The p+ contact region CON is in contact with the p-type base region BR.The p+ contact region CON has a p-type impurity concentration higherthan a p-type impurity concentration of the p-type base region BR. Then+ emitter region ER configures the pn junction with each of the p+contact region CON and the p-type base region BR.

A trench TR is formed in the semiconductor substrate SB. The trench TRpenetrates through each of the n+ emitter region ER and the p-type baseregion BR from the second main surface SMS and reaches the n− driftregion DRI. A gate dielectric layer GI is arranged along an inner wallof the trench TR. An inside of the trench TR is filled with the gateelectrode GE. The gate electrode GE faces the p-type base region BR viathe gate dielectric layer GI. Thus, the IGBT has an insulated gate fieldeffect transistor portion.

An emitter electrode EE is arranged so as to be electrically connectedto each of the n+ emitter region ER and the p+ contact region CON via acontact hole CH of an interlayer insulating layer IL. The emitterelectrode EE includes a barrier metal layer BM and the metal film MF.The barrier metal layer BM is in contact with the n+ emitter region ERand the p+ contact region CON via the contact hole CH. The metal film MFis in contact with the barrier metal layer BM.

A collector electrode CE is arranged on the first main sur face FMS ofthe semiconductor substrate SB. The collector electrode CE iselectrically connected to the p+ collector region CR by being in contactwith the p+ collector region CR.

The metal film MF shown in FIG. 1 is used, for example, as the metalfilm MF of the IGBT shown in FIG. 2 . The metal film MF shown in FIG. 2functions as an emitter pad (bonding pad) and a wiring in the IGBT. Forthis purpose, the metal film MF shown in FIG. 1 is used as the bondingpad and the wiring in the IGBT shown in FIG. 2 . And the metal film MFshown in FIG. 1 may also be used for other bonding pads such as a gatepad and other wiring in the IGBT.

In addition to the IGBT shown in FIG. 2 , the metal film MF shown inFIG. 1 may be used for a bonding pad such as a source pad, the gate padand a wiring of a power MOSFET (Metal Oxide Semiconductor Field EffectTransistor) As shown in FIG. 3 , the semiconductor device SD accordingto the present embodiment is, for example, a semiconductor package inwhich a semiconductor chip SC is sealed with a sealing resin SRE. Thesemiconductor device SD of the present embodiment includes a chipmounting portion RB, the semiconductor chip SC, lead portions RD1 andRD2, bonding wires BW (BW1, BW2) and the sealing resin SRE.

The semiconductor chip SC has the IGBT and the metal film MF shown inFIG. 2 . The semiconductor chip SC has the emitter pad EP electricallyconnected to the n+ emitter region ER of the IGBT (FIG. 2 ) and the gatepad GP electrically connected to the gate electrode GE of the IGBT. Eachof the emitter pad EP and the gate pad GP is configured by the metalfilm MF shown in FIG. 1 .

The semiconductor chip SC is mounted on the chip mounting portion RBwith a solder SOL interposed therebetween. Each of the lead portions RD1and RD2 is arranged spaced apart from the chip mounting portion RB. Thebonding wire BW1 electrically connects the emitter pad EP of thesemiconductor chip SC and the lead portion RD1. Although only onebonding wire BW1 is shown for simplicity of illustration, a plurality ofbonding wires BW1 may be connected between the emitter pad EP and thelead portion RD1. The bonding wire BW2 electrically connects the gatepad GP of the semiconductor chip SC and the lead portion RD2.

The sealing resin SRE seals the chip mounting portion RB, thesemiconductor chip SC, the lead portions RD1 and RD2, a clip conductorCC, and the bonding wires BW (BW1, BW2). A part of each of the chipmounting portion RB and the lead portions RD1 and RD2 is exposed fromthe sealing resin SRE. The sealing resin SRE is made of, for example, athermosetting resin material, and may include, for example, a filler(for example, a filler made of silica particles).

(A Manufacturing Method of the Metal Film and the Semiconductor Device)

Next, a manufacturing method of the metal film and the semiconductordevice according to a present embodiment will be described withreference to FIG. 4 to FIG. 6 .

As shown in FIG. 4 , the metal film MF made of a material containing atleast one selected from the group consisting of aluminum, tungsten,copper, cobalt, and nickel is formed. The metal film MF is formed of amaterial including, for example, aluminum, pure aluminum, an alloy ofaluminum and silicon, an alloy of aluminum and copper, or an alloy ofaluminum, silicon, and copper.

The metal film MF is formed by, for example, sputtering. The metal filmMF is formed to have a thickness of, for example, 1 micrometer or moreand 4 micrometers or less. The metal film MF is formed to have aplurality of metal crystal grains GR. Large internal stress is generatedinside the metal film MF.

As shown in FIG. 5 , for example, vacancies V are introduced as thepoint defects in the metal film MF. It is believed that the vacancies Vintroduced into the metal film MF diffuse due to the large innerstresses in the metal film MF.

The vacancies V are introduced, for example, by an ion-implantation ofmetal ions into the metal film MF. The ion-implantation is performed,for example, at a dose of 1×10¹⁶ cm⁻² or more and less than 1×10¹⁸ cm⁻².An implantation energy of the ion-implantation is, for example, 100 keVor more, but can be appropriately changed in accordance with animplantation depth or the like. The metal ions to be ion-implanted are,for example, any one or any combination of aluminum, silicon, copper,tungsten, cobalt and nickel.

The vacancies V may be introduced, for example, by irradiating the metalfilm MF with an electron-beam. The vacancies V may also be introducedinto the metal film MF by a combination of the ion-implantation andelectron-beam illumination.

As shown in FIG. 6 , annealing is performed on the metal film MF afterthe introduction of the point defects (vacancies V). This annealing isperformed, for example, in an atmosphere of an inert gas at a heatingtemperature of 300 degrees Celsius or higher and 400 degrees Celsius. orlower for a heating time of less than 2 hours. Annealing recrystallizesa plurality of the metal crystal grains GR of the metal film MF.Recrystallization of the metal crystal grains GR generates dislocationsDL in the metal film MF.

Although the metal film MF is plastically deformed by theabove-mentioned annealing, it is considered that a plastic deformationis accelerated by the point defects (vacancies V), so that the vacanciesV are gathered in some metal crystal grains and dislocations DL aregenerated.

As a result, a second metal crystal grain GR11 having no dislocations DLand first metal crystal grains GR12 and GR13 having the dislocations DLare formed in the plurality of metal crystal grains GR. In addition, anumber of the first metal crystal grains GR12 and GR13 having thedislocations DL is larger than the number of the second metal crystalgrain GR11 having no dislocations DL.

The metal film MF of the present embodiment is manufactured by theabove-described steps. Note that, in the ion-implantation of FIG. 5 ,for example, silicon or the like is implanted into the metal film MFmade of a material containing aluminum. In this case, the implantedsilicon or the like is diffused by the heat and the implantation energyduring the ion-implantation. The diffused silicon or the like diffusesto the grain boundaries GB of the metal crystal grains GR as shown inFIG. 1 and precipitates as the third metal crystal grains GRA.

In addition, the ion-implantation shown in FIG. 5 may be performed on anentire surface of the metal film MF, or may be performed only on someregions of the metal film MF. The ion-implantation may be selectivelyperformed at a portion where the bonding wires BW are connected to themetal film MF, for example.

In this case, as shown in FIG. 7 , the ion-implantation is performedwith a photoresist mask PM formed on the metal film MF. The photoresistmask PM has a plurality of openings PRA that expose the front face ofthe metal film MF. Each of the plurality of openings PRA have, forexample, a rectangular planar shape. Each of the plurality of openingsPRA may have, for example, a circular planar shape. The opening area ofeach of the plurality of openings PRA may be the same as or differentfrom each other.

The surface of the metal film MF exposed by the openings PRA are wherethe bonding wires BW are connected. By performing the above-describedannealing after at least ion-implantation at a portion where the bondingwires BW are connected, a portion where the bonding wires BW areconnected can be locally cured, and crack resistance can be improved.

When the ion-implantation is selectively performed in this manner, inregions of the metal film MF where the ion-implantation is selectivelyperformed, a number of metal grains having the dislocations DL is largerthan a number of metal grains having no dislocations DL. On the otherhand, when the ion-implantation is performed on an entire surface of themetal film MF, the number of metal crystal grains having thedislocations DL is larger than the number of metal crystal grains havingno dislocations DL in the entire metal film MF.

The semiconductor device shown in FIG. 2 is manufactured using amanufacturing method of the metal film MF of the present embodiment. Forexample, the semiconductor device shown in FIG. 2 is manufactured byforming the metal film MF of the present embodiment as the bonding pador the wiring.

Specifically, as shown in FIG. 2 , for example, the IGBT is formed inthe semiconductor substrate SB. After the IGBT is formed, the interlayerinsulating layer IL is formed on the second main surface SMS of thesemiconductor substrate SB. In the interlayer insulating layer IL, thecontact hole CH is formed by a photolithography technique and an etchingtechnique. The contact hole CH is formed so as to expose the respectivesurfaces of the n+ emitter region ER and the p+ contact region CON.Although not shown in the drawings, the contact hole CH exposing a partof the gate electrode GE is also formed in the interlayer insulatinglayer IL.

The barrier metal layer BM is formed on the interlayer insulating layerIL so as to be in contact with each of the n+ emitter region ER and thep+ contact region CON through the contact hole CH. And the barrier metallayer BM in contact with the gate electrode GE through the contact holeCH is also formed. The metal film MF to become as the wiring and thebonding pad (emitter pad or gate pad) is formed so as to be in contactwith the barrier metal layer BM. This metal film MF is the metal film MFmanufactured by the process shown in FIGS. 4 to 6 .

(Effect)

Next, the effect of the present embodiment will be described togetherwith the findings found out by the inventor of the present disclosure.

First, the inventor of the present disclosure formed the metal film MFmade of aluminum and copper (AlCu) by sputtering, prepared a samplewithout performing the ion-implantation on the metal film MF and asample with the ion-implantation, and observed their cross-sections.

As a result, as shown in FIG. 8 , a dense point defect is not observedin the sample without the ion-implantation. In contrast, as shown inFIG. 9 , in a sample in which aluminum is ion-implanted at animplantation energy 100 keV and a dose of 1×10¹⁶ cm⁻², the point defectsdense from the front surface of the metal film MF to a depth of 300 nmto 400 nm (dotted line DOL) are observed. Further, as shown in FIG. 10 ,even in a sample in which silicon is ion-implanted at an implantationenergy 100 keV and a dose of 1×10¹⁶ cm⁻², the point defects denselypacked from the front surface of the metal film MF to the depth of 300nm to 400 nm (dotted line DOL) are observed.

In addition, the inventor of the present disclosure performed annealingon samples of the metal film MF made of aluminum and copper and observedthem cross section. Here, one sample is performed the ion-implantationand other sample is not performed the ion-implantation. The annealing isperformed in an atmosphere of an inert gas at a heating temperature of300 degrees Celsius. or higher and 400 degrees Celsius. or lower for aheating time of less than 2 hours.

As a result, as shown in FIG. 11 , in the sample in which theion-implantation is not performed, although the dislocations areobserved, it is found that the number of dislocation-generated metalcrystal grains is extremely small. On the other hand, as shown in FIG.12 , in a sample in which aluminum is ion-implanted under the conditionsof an implantation energy 180 keV and a dose of 1×10¹⁶ cm⁻², thedislocations occurred in many metal crystal grains, and it is found thata dislocation density is higher than that in a sample in which theion-implantation is not performed. In addition, as shown in FIG. 13 ,even in a sample in which silicon is ion-implanted under the conditionsof a implantation energy 180 keV and a dose of 1×10¹⁶ cm⁻², thedislocations occurred in many metal crystal grains, and it is found thatthe dislocation density is higher than that in a sample in which theion-implantation is not performed.

Furthermore, in the sample in which the ion-implantation as shown inFIGS. 12 and 13 is performed, it is also found that the number of themetal crystal grains having the dislocations is larger than the numberof the metal crystal grains having no dislocations.

And, the inventor of the present disclosure investigated therelationship between the presence or absence of the ion-implantationinto the metal film MF and the relaxation of stress. The result is shownin FIG. 14 .

From the results of FIG. 14 , it is found that warpages of the samples 1and 2 in which ions are implanted into the metal film MF is smaller thanthat of the comparative example in which the ion-implantation is notperformed in the metal film MF, and the inner stresses in the metal filmMF are relaxed. In particular, it is found that the warpage in thesample 2 after annealing is 34% smaller than the warpage in the sampleof the comparative example after annealing.

Note that each of sample 1, sample 2, and comparative example are themetal film MF made of aluminum deposited at a thickness of 1 micrometerby sputtering at 250 degrees Celsius. Sample 1 is a sample in whichaluminum is ion-implanted at an implantation energy 180 keV and a doseof 1×10¹⁶ cm⁻². Sample 2 is a sample in which silicon is ion-implantedat an implantation energy 180 keV and a dose of 1×10¹⁶ cm⁻². Annealingis performed in an inert gas atmosphere at a heating temperature of 400degrees Celsius. for a heating time of 30 minutes.

The inventor of the present disclosure also examined the dislocationdensity and hardness in Sample 1, Sample 2, and comparative exampleafter annealing in FIG. 14 . As a result, the sample of the comparativesample had a dislocation density of 28 particles/square micrometer and ahardness of 0.92 GPa. In contrast, Sample 1 had a dislocation density of60 particles/square micrometer and a hardness of 0.96 GPa. In Sample 2had a dislocation density of 75 particles/square micrometer and ahardness of 1.17 GPa.

In addition, the inventor of the present disclosure has confirmed thatthe crystal orientation and resistance of the metal film MF that hasbeen annealed for recrystallization are equivalent to the crystalorientation and resistance of the metal film MF that has not beenion-implanted, and there is no practical problem.

The dislocation density is obtained by observing the cross section ofthe metal film MF by TEM (Transmission Electron Microscopy) and countingthe number of the dislocations. The mean crystal grain size is obtainedby observing the metal film MF from above by SEM (Scanning ElectronMicroscope) to determine the area of the crystal grain, and calculatingthe diameter of a perfect circle corresponding to the area.

As described above, the inventor of the present disclosure has foundthat high density dislocations occur in the metal film MF by introducingthe point defects (vacancies V) by implanting the metal ions into themetal film MF and then performing annealing of recrystallization. Thereason why the high density dislocations occurred is considered that,although, the metal film MF undergoes the plastic deformation due toannealing, the introduced the point defects (vacancies V) acceleratethis plastic deformation and gathered in some crystal grains. Further,the inventor of the present disclosure have found that the crackresistance of wire bonding is improved by hardening the metal film MF bythe high density dislocations to obtain high strength.

In the present embodiment, the number of the first metal crystal grainsGR2, GR3 and GR4 having dislocations DL is larger than the number of thesecond metal crystal grains GR1 and GR5 having no dislocations DL.Therefore, the metal film MF has high strength, and the crack resistanceof the wire bonding is improved.

In the present embodiment, the metal film MF is made of a materialcontaining at least one selected from the group consisting of aluminum,tungsten, copper, cobalt, and nickel. As a result, the metal film MF canbe applied to the wiring and the bonding pad. Note that, by using amaterial containing aluminum as the metal film MF, high crack resistancecan be obtained in wire bonding.

In the present embodiment, the dislocations DL in each of the firstmetal crystal grains GR2, GR3 and GR4 is 60 dislocations/squaremicrometer or more. As a result, cracks are less likely to occur in wirebonding.

In the present embodiment, the mean crystal grain size of the pluralityof metal crystal grains GR including the first metal crystal grains GR2,GR3 and GR4, and the second metal crystal grains GR1 and GR5 is 1micrometer or more and 5 micrometers or less. When the mean crystalgrain size is less than 1 micrometer, the grain boundaries become largeand the electromigration resistance and the stress migration resistancebecome low. When the mean crystal grain size exceeds 5 micrometers, thehardness decreases.

In the present embodiment, the mean crystal grain size of the metalcrystal grains GR is 1.7 micrometers or less. This improves thehardness.

Further, in the present embodiment, as shown in FIG. 1 , the third metalcrystal grains GRA are located in the grain boundaries GB of theplurality of metal crystal grains GR including the first metal crystalgrains GR2, GR3 and GR4, and the second metal crystal grains GR1 andGR5. The third metal crystal grains GRA are located at the grainboundaries GB in this way, so that the metal element in the metal filmMF is less likely to move. This improves electromigration resistance andstress migration resistance.

Further, in the present embodiment, each of the first metal crystalgrains GR2, GR3 and GR4, and the second metal crystal grains GR1 and GR5is made of a material containing aluminum, and the third metal crystalgrains GRA are made of a material containing silicon or copper. Thus,the third metal crystal grains GRA can be precipitated at the grainboundaries of the plurality of metal crystal grains GR.

In addition, in the present embodiment, as shown in FIG. after the pointdefects (vacancies V) are introduced into the metal film MF, the metalcrystal grains GR are recrystallized as shown in FIG. 6 , wherebydislocations DL are generated in the metal film MF. As a result, thehigh-density dislocations can be generated, so that metal film MF hashigh strength, and the crack resistance of the wire bonding is improved.

Further, in the present embodiment, the step of introducing the pointdefects (vacancies V) into the metal film MF includes at least one of astep of implanting a metal-ion into the metal film MF and a step ofirradiating the metal film MF with an electron-beam. As a result, thepoint defects (vacancies V) can be introduced into the metal film MF.

In addition, the wiring of aluminum is required to have a highelectromigration resistance and a high stress migration resistance whena large current flows in the power device. In aluminum films formed byconventional sputtering, it is difficult to achieve both crackresistances, electromigration resistance, and stress migrationresistance.

However, according to the present embodiment, as described above, it iseasy to achieve both crack resistances, electromigration resistance, andstress migration resistance.

Although the invention made by the present inventor has beenspecifically described based on the embodiment, the present invention isnot limited to the embodiment described above, and it is needless to saythat various modifications can be made without departing from the gistthereof.

What is claimed is:
 1. A metal film comprising: a plurality of firstmetal crystal grains having dislocations and a plurality of second metalcrystal grains not having the dislocations, wherein a number of theplurality of first metal crystal grains is greater than a number of theplurality of second metal crystal grains.
 2. The metal film according toclaim 1, wherein the metal film made of a material containing at leastone selected from a group consisting of aluminum, tungsten, copper,cobalt and nickel.
 3. The metal film according to claim 1, wherein adensity of the dislocations of the plurality of first metal crystalgrains is 60 particles/square micrometer or more.
 4. The metal filmaccording to claim 1, wherein a mean crystal grain size of a pluralityof metal crystal grains including the plurality of first metal crystalgrains and the plurality of second metal crystal grains is 1 micrometeror more and 5 micrometers or less.
 5. The metal film according to claim4, wherein the mean crystal grain size of the plurality of metal crystalgrains is 1.7 micrometers or less.
 6. The metal film according to claim1, further comprising: a plurality of third metal crystal grains locatedon grain boundaries of the plurality of metal crystal grains includingthe plurality of first metal crystal grains and the plurality of secondmetal crystal grains, wherein the plurality of third metal crystalgrains made of a different material of the plurality of first metalcrystal grains and the plurality of second metal crystal grains.
 7. Themetal film according to claim 6, wherein the plurality of first metalcrystal grains and the plurality of second metal crystal grains made ofa material containing aluminum and the plurality of third metal crystalgrains made of a material containing silicon or copper.
 8. Asemiconductor device comprising: a metal film including a plurality offirst metal crystal grains each having dislocations and a plurality ofsecond metal crystal grains each not having the dislocations, whereinthe metal film is comprised as a bonding pad or a wiring.
 9. Amanufacturing method of a metal film, comprising the steps of: (a)forming a metal film having a plurality of metal crystal grains; (b)forming point defects in the metal film; and (c) after the step of (b),generating dislocations in the metal film by annealing so as torecrystallize the plurality of metal crystal grains.
 10. Themanufacturing method of the metal film, according to claim 9, wherein inthe step of (c), a plurality of first metal crystal grains having thedislocations and a plurality of second metal crystal grains not havingthe dislocations are made in the metal film, and a number of theplurality of first metal crystal grains is greater than a number of theplurality of second metal crystal grains.
 11. The manufacturing methodof the metal film, according to claim 9, wherein in the step of (b),including at least one step of steps of (b1) implanting a metal ion intothe metal film and (b2) irradiating an electron beam to the metal film.